DP1/2M with Eye-fi X2 Pro?
I gave this a try and I've been meaning to write up a review at some point, but I'll run down my findings.
First, let me say that it works with the DP2 and DP1 Merrill cameras. It will definitely impact your battery life. The last time I used it I fired off around 62 images before my battery indicator showed no bars left. It hadn't gone into the red yet, but the camera was pretty warm to the touch by the end.
General setup of the card can be a bit confusing. If you just want to hook the card up to your home WiFi, then it's a bit easier as you have an app running on your Mac/PC that pulls down the JPEG and X3F files (I picked up the Pro X2 8GB).
It seems you have to use the card reader it came with in order to program the card. I tried plugging in the card into the SD slot directly in my Macbook Pro, but all it seemed to do was to power the WiFi in the card to the point that the images would then be transferred over WiFi back to the same laptop.
You can set the card to use a direct mode where you use your smartphone to connect to the card's WiFi directly. You can configure the card to only transfer JPEG files and not the X3F RAW files or movies. I did this the day I was able to get 62 shots as mentioned above. It was pretty cool. As I shot RAW+JPEG on the DP1M the JPEGs would show up on my iPhone.